Because, in these days, energy saving of a refrigerator and manufacture of a large-sized refrigerator are globally carried out, it is rapidly progressing to increase the use of a vacuum insulator in the refrigerator regardless of the home and abroad. The vacuum insulator is manufactured by covering a core material having a fine and communicating space inside glass wool or a silica powder, for example, with an outer envelope having a gas barrier property and by decompressing and sealing an inside of the outer envelope.
In order to reduce the thickness of insulation of the refrigerator for the purpose of the large-sized refrigerator, an initial performance of an insulator to be used needs to be improved in terms of acquisition of an energy saving performance. Also, because, due to the reduced thickness of insulation of the refrigerator, dew condensation occurs easily in the surface of the refrigerator in a high-temperature and high-humidity environment, an insulation performance of the vacuum insulator needs to be maintained for a long term so as to prevent dew condensation.
In the vacuum insulator, gas including air or vapor that remains in the vacuum insulator after vacuum discharge is performed, is one factor that causes thermal conduction. In addition, gas is introduced into the vacuum insulator through the outer envelope from the outside so that a degree of vacuum inside the vacuum insulator is deteriorated and the insulation performance of the vacuum insulator is lowered. Thus, an adsorbent is disposed in the vacuum insulator and adsorbs the gas so that the degree of vacuum inside the vacuum insulator is maintained.
In order to improve the performance of the vacuum insulator using the adsorbent, both a configuration of removing an inside gas that remains in the vacuum insulator after vacuum discharge is performed, in early stages and a configuration of removing gas introduced into the vacuum insulator from the outside for a long term are required.
As a configuration of the adsorbent for removing an inside gas that remains in the vacuum insulator in early stages after vacuum discharge is performed. This document discloses that an adsorbent is disposed in the floor of a plurality of insertion holes formed from the surface of a core material at regular intervals so that an adsorption time of moisture and gas components in the core material can be reduced.
In addition, as a configuration of removing gas introduced into the vacuum insulator from the outside for a long term. This document discloses that, in a non-adsorbent gas atmosphere, a zeolite-based adsorbent is hermetically packed in a non-porous sack, a porous hole is formed in the non-porous sack and then vacuum discharge is performed so that a degree of vacuum can be maintained and deterioration of an insulation performance can be prevented.